In a magnetic disk device with a plurality of disk surfaces, a head stack assembly (HSA) which holds a plurality of magnetic heads is provided so as to correspond to each disk surface. The magnetic head includes a plurality of elements, such as a reading element, a writing element, a heater element, an element for assisted recording. When the number of elements provided in each magnetic head increases, the space of the bonding portions of wiring lines connected to the elements increases. As a result, the structure of the head stack assembly becomes complicated and the size thereof increases.